End Show Slide 1 of 38 Copyright Pearson Prentice Hall Prentice Hall Biology

End Show Slide 2 of 38 Copyright Pearson Prentice Hall 10-2 Cell Division

End Show 10-2 Cell Division Slide 3 of 38 Copyright Pearson Prentice Hall In eukaryotes, cell division occurs in two major stages. The first stage, division of the cell nucleus, is called mitosis. The second stage, division of the cell cytoplasm, is called cytokinesis. Cell Division

End Show 10-2 Cell Division Slide 4 of 38 Chromosomes Genetic information is passed from one generation to the next on chromosomes. Before cell division, each chromosome is duplicated, or copied.

End Show 10-2 Cell Division Slide 5 of 38 Chromosomes Copyright Pearson Prentice Hall

End Show 10-2 Cell Division Slide 6 of 38 Copyright Pearson Prentice Hall Chromosomes Each chromosome consists of two identical “sister” chromatids. Each pair of chromatids is attached at an area called the centromere. Sister chromatids Centromere

End Show 10-2 Cell Division Slide 7 of 38 Copyright Pearson Prentice Hall Chromosomes When the cell divides, the chromatids separate. Each new cell gets one chromatid.

End Show 10-2 Cell Division Slide 8 of 38 Copyright Pearson Prentice Hall The Cell Cycle Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide. Interphase is the period of growth that occurs between cell divisions.

End Show 10-2 Cell Division Slide 9 of 38 Copyright Pearson Prentice Hall The Cell Cycle During the cell cycle: a cell grows prepares for division divides to form two daughter cells, each of which begins the cycle again

End Show 10-2 Cell Division Slide 10 of 38 Copyright Pearson Prentice Hall The Cell Cycle The cell cycle consists of four phases: G 1 (First Gap Phase) S Phase G 2 (Second Gap Phase) M Phase

End Show 10-2 Cell Division Slide 11 of 38 Copyright Pearson Prentice Hall Events of the Cell Cycle During G 1, the cell increases in size synthesizes new proteins and organelles

End Show 10-2 Cell Division Slide 12 of 38 Copyright Pearson Prentice Hall Events of the Cell Cycle During the S phase, chromosomes are replicated DNA synthesis takes place Once a cell enters the S phase, it usually completes the rest of the cell cycle.

End Show 10-2 Cell Division Slide 13 of 38 Copyright Pearson Prentice Hall Events of the Cell Cycle The G 2 Phase (Second Gap Phase) organelles and molecules required for cell division are produced Once G 2 is complete, the cell is ready to start the M phase—Mitosis

End Show 10-2 Cell Division Slide 14 of 38 Copyright Pearson Prentice Hall Cell Cycle Events of the Cell Cycle

End Show 10-2 Cell Division Slide 15 of 38 Copyright Pearson Prentice Hall Mitosis Biologists divide the events of mitosis into four phases: (PMAT) Prophase Metaphase Anaphase Telophase

End Show 10-2 Cell Division Slide 16 of 38 Copyright Pearson Prentice Hall Mitosis

End Show 10-2 Cell Division Slide 17 of 38 Copyright Pearson Prentice Hall Section 10-2 Prophase Spindle forming Chromosomes (paired chromatids) Centromere Click to Continue Mitosis Prophase

End Show 10-2 Cell Division Slide 18 of 38 Copyright Pearson Prentice Hall Mitosis Prophase Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. Spindle forming Centromere Chromosomes (paired chromatids)

End Show 10-2 Cell Division Slide 19 of 38 Copyright Pearson Prentice Hall Mitosis The centrioles lie in a region called the centrosome. The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes. Spindle forming Centromere Chromosomes (paired chromatids)

End Show 10-2 Cell Division Slide 20 of 38 Copyright Pearson Prentice Hall Mitosis Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. The nuclear envelope breaks down. Spindle forming Centromere Chromosomes (paired chromatids)

End Show 10-2 Cell Division Slide 21 of 38 Copyright Pearson Prentice Hall Centriole Spindle Mitosis Click to Continue Metaphase

End Show 10-2 Cell Division Slide 22 of 38 Copyright Pearson Prentice Hall Mitosis Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the poles of the spindle. Centriole Spindle

End Show 10-2 Cell Division Slide 23 of 38 Copyright Pearson Prentice Hall Individual chromosomes Anaphase Mitosis Anaphase

End Show 10-2 Cell Division Slide 24 of 38 Copyright Pearson Prentice Hall Mitosis Anaphase Anaphase is the third phase of mitosis. The sister chromatids separate into individual chromosomes. The chromosomes continue to move until they have separated into two groups. Individual chromosomes

End Show 10-2 Cell Division Slide 25 of 38 Copyright Pearson Prentice Hall Nuclear envelope reforming Telophase Mitosis Telophase

End Show 10-2 Cell Division Slide 26 of 38 Copyright Pearson Prentice Hall Mitosis Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape.

End Show 10-2 Cell Division Slide 27 of 38 Copyright Pearson Prentice Hall Mitosis A new nuclear envelope forms around each cluster of chromosomes.

End Show 10-2 Cell Division Slide 28 of 38 Copyright Pearson Prentice Hall Cytokinesis

End Show 10-2 Cell Division Slide 29 of 38 Copyright Pearson Prentice Hall Cytokinesis During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes

End Show 10-2 Cell Division Slide 30 of 38 Copyright Pearson Prentice Hall Cytokinesis in Plants In plants, a structure known as the cell plate forms midway between the divided nuclei. Cell wall Cell plate

End Show 10-2 Cell Division Slide 31 of 38 hill.com/sites/ /student_view0/c hapter28/animation__how_meiosis_works. html

End Show 10-2 Cell Division Slide 32 of 38 **Meiosis II (con)**Meiosis II (con)

End Show 10-2 Cell Division Slide 33 of 38 Spermatogenesis In testes Produces 4 genetically different haploid spermatids Spermatids mature into sperm

End Show 10-2 Cell Division Slide 34 of 38 Oogenesis In ovaries Produces –1 Egg –3 Polar Bodies Unequal Cytoplasm Division

End Show 10-2 Cell Division Slide 35 of 38 Spermatogenesis vs Oogenesis

End Show 10-2 Cell Division Slide 36 of 38 **Mitosis vs Meiosis**

End Show 10-2 Cell Division Slide 37 of 38 Asexual & Sexual Reproduction Asexual Offspring from 1 parent Unicellular  mitosis or budding Multicellular  budding Always genetically identical to parent Sexual Offspring results from union of gametes= zygote Offspring genetically different from parents due to meiosis recombining genes Allows species to adapt more quickly